The present invention relates generally to gas turbines, and more particularly to a gas turbine subassembly having a brush seal.
Gas turbines include combustion-type gas turbines, which utilize combustion gases to turn rotors, and steam-type gas turbines, which utilize steam to turn rotors. Examples of gas turbines include, but are not limited to, gas-turbine power-generation equipment and gas-turbine aircraft engines. A combustion-type gas turbine has a gas path which typically includes, in serial-flow relationship, an air intake (or inlet), a compressor, a combustor, a turbine, and a gas outlet (or exhaust nozzle). A steam-type gas turbine has a gas path which typically includes a steam inlet, a turbine, arid a steam outlet.
Compressors and turbines include rotating rotors rotatably attached to surrounding non-rotating stator by suitable bearings. Gas paths between compressors and combustor and between combustor and turbines include annular transition ducts having radially inner and outer stator portions. At certain axial locations, rotors typically include radially-outwardly projecting rotor blades, and at certain axial locations, stator typically include radially-inwardly projecting stator vanes. Some gas turbines include high and low pressure compressors and high and low pressure turbines with the high pressure compressor rotor surrounding the low pressure compressor rotor and with the high pressure turbine rotor surrounding the low pressure turbine rotor.
Gas leakage between certain gas-turbine components is undesirable because it wastes gas (e.g., air, combustion gas, steam, etc.) Causing a loss in power and efficiency. For example, such loss in power and efficiency occurs due to gas leakage between the radially-overlapping portions of the compressor rotor and the radially inner stator of the associated annular duct which directs gas downstream towards the combustor. Also, such loss in power and efficiency occurs due to gas leakage past a rotor/stator or rotor/rotor bearing with additional problems including overheating of the bearing causing excessive oil use.
Conventional gas-turbine power-generation equipment includes a gas turbine having a honeycomb-labyrinth seal whose labyrinth hard teeth are attached to the radially-underlapping portion of the compressor and whose honeycomb segment is attached to the radially-overlapping portion of the inner stator of the associated annular duct which directs gas downstream towards the combustor. It is known that the labyrinth hard teeth will abrade away a portion of the honeycomb segment due to differertial thermal movement during shutdown.
Conventional gas turbine aircraft engines include gas turbines which have used annular brush seals between stator and rotors. Although a brush seal affords better sealing than any labyrinth seal (including a honeycomb-labyrinth seal), the free ends of such seals became damaged and worn during engine operation. One known cause is damaging contact caused by aircraft engine vibration. Another known cause is contact-wear caused by differential thermal movement when the engine transitions between two different operating states.
What is needed is a gas turbine subassembly which has a brush seal and which reduces or eliminates brush seal wear.